Lightweight Low-Profile Vent Systems for Aircraft Fluid Dispersion Tanks

ABSTRACT

In the field of agriculture and aerial firefighting, some example vent systems for aircraft fluid dispersion tanks include a vent-well recessed below the top of the tank. When a gate valve assembly below the tank opens to release fluid for dispersion along the aircraft&#39;s trailing flight path, the vent system prevents a detrimental vacuum from developing within the tank. In some examples, a recessed vent exploits the Coanda effect to direct air into the tank without obstructing the pilot&#39;s view. In some examples, a low profile scoop above the vent further promotes airflow with minimal visual obstruction. In addition or alternatively, some example vent systems include a lightweight cable connecting the gate valve assembly to a spring-loaded vent. The cable pulls the vent open in response to the gate opening to release fluid. When the gate closes, the cable becomes slack, which allows the spring to close the vent.

FIELD OF THE DISCLOSURE

This patent generally pertains to agricultural and firefighting productdispersal systems of aircraft and more specifically to means for ventingthe tanks that contain the product.

BACKGROUND

Some aircraft (e.g., airplanes and helicopters) are used as crop dustersor air tankers for agricultural and/or firefighting purposes. Suchaircraft typically include a bulk container (e.g., a tank or a hopper)for carrying a flowable bulk product, such as dry fertilizer, liquidfertilizer, pesticide, fire extinguishing liquid, water, etc.

To selectively release the product, in some examples, a linkage assemblyconnects a manually operated lever in the cockpit to a movable gate atan outlet of the bulk container. The pilot operates the lever to openand close the gate, and thereby controls the release of the bulkproduct. When released, the bulk product is dispersed along theaircraft's trailing flight path. A vent near the top of the containercan facilitate the release of product from the container.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of an example aircraft with an example vent systemconstructed in accordance with the teachings disclosed herein, whereinthe vent system is shown closed.

FIG. 2 is a side view similar to FIG. 1 but showing the aircraftdispersing fluid while the vent system is open.

FIG. 3 is a perspective view showing various axes of an aircraft.

FIG. 4 is a cross-sectional view taken along line 4-4 of FIG. 1 .

FIG. 5 is a perspective view of the example vent system shown in FIG. 1, wherein parts of a tank and gate valve assembly are schematicallyillustrated.

FIG. 6 is a perspective view similar to FIG. 6 but showing the ventsystem open.

FIG. 7 is a cross-sectional side view of an example vent systemconstructed in accordance with the teachings disclosed herein.

FIG. 8 is a cross-sectional side view similar to FIG. 7 but showing thevent system open while operating in a second mode of operation.

FIG. 9 is a cross-sectional side view similar to FIG. 8 but showing thescoop of an upstream vent directing air into a downstream vent.

FIG. 10 . is a cross-sectional side view similar to FIG. 8 but showingan even lower profile vent system constructed in accordance with theteachings disclosed herein.

FIG. 11 is a cross-sectional side view similar to FIG. 7 but showinganother example vent constructed in accordance with the teachingsdisclosed herein.

FIG. 12 is a cross-sectional side view similar to FIG. 11 but showingthe vent in an unsealed position while operating in a second mode ofoperation.

FIG. 13 is a cross-sectional side view similar to FIG. 11 but showingthe vent system operating in a first mode of operation.

FIG. 14 is a cross-sectional side view similar to FIG. 7 but showing thevent system operating in a first mode of operation.

DETAILED DESCRIPTION

FIGS. 1-9 pertain to a vent system 10 for a fluid dispersion tank 12 ofan aircraft 14, wherein aircraft 14 is used for dispersing a fluid 16 orother flowable product while in-flight. A gate valve assembly 18 at thebottom of tank 12 includes at least one gate 20 that opens to releasefluid 16 from tank 12. Gate 20 is movable between a closed position(FIGS. 1, 4, 5, 7, 11 and 12 ) to retain fluid 16 and an open position(FIGS. 2, 6, 8, 9, and 10 ) to release fluid 16. When gate 20 opens, itreleases fluid 16 from tank 12 while vent system 10 prevents adetrimental vacuum from developing within tank 12. The released fluid 16is dispersed along the aircraft's trailing flight path. Such a system isparticularly suited for agricultural and firefighting purposes.

The term, “aircraft” refers to any flying machine. Some examples ofaircraft 14 include an aerial crop duster, air tanker, an airplane, ahelicopter, an Air Tractor AT402, an Air Tractor AT502, an Air TractorAT602, an Air Tractor AT802A, an Air Tractor AT802F, a Thrush aircraft,and a Dromodier aircraft.

The term, “fluid” refers to any product or material that can flow. Someexamples of fluid 16 include a liquid, granules, particles, seed,powder, water, chemical mixtures, fertilizer, pesticide, and fireretardant.

The term, “tank” refers to any hollow structure for containing a fluid.Some examples of tank 12 include a vessel, a hopper, a container, areceptacle, etc. In the illustrated examples, tank 12 defines a chamber22 for containing fluid 16. In some examples, tank 12 is filled withfluid 16 through a fill valve 112 at a port 24 on either tank 12 or gateassembly 18.

The term, “gate” refers to any member that can be moved relative to anopening to vary the flow of a fluid through the opening or selectivelystop (or substantially stop) the flow. Some example gates includeplates, plugs, flaps, diaphragms, etc. Some example modes of gatemovement include translating, pivoting, expanding, contracting, bending,and various combinations thereof. Some examples of gate assembly 18include those disclosed in U.S. Pat. No. 11,046,433 and U.S. patentapplication Ser. Nos. 17/202,577 and 17/386,721; all of which arespecifically incorporated herein by reference. In some examples, gate 20is a 5-inch, 7.5-inch or 10-inch wide gate provided by Transland ofWichita Falls, Tex. In some examples, gate 20 is one of a series ofgates in a gate assembly, wherein the gates open and close in unison.Gate 20 and gate assembly 18 are schematically illustrated in FIGS. 5-12.

For describing physical orientations and relative positions, certaincomponents of vent system 10 are described herein with reference toknown orthogonal axes of aircraft 14, as shown in FIG. 3 . FIG. 3 showsaircraft 14 comprising a nose 26, a tail 28, a cockpit 30, and awindshield 32. Aircraft 14 defines a roll axis 34, a pitch axis 36, anda yaw axis 38. Aircraft 14 extends lengthwise along roll axis 34 in aforward direction 40 from tail 28 to nose 26. Windshield 32 facesgenerally in forward direction 40. Aircraft 14 extends laterallywidthwise along pitch axis 36. Aircraft 14 extends along yaw axis 38 inan upward direction 42 from a lower portion 44 of aircraft 14 to anupper portion 46 of aircraft 14. Cockpit 30 is between tail 28 and nose26 with respect to roll axis 34. Roll axis 34, yaw axis 38, and pitchaxis 36 lie perpendicular to each other.

In some examples, vent system 10 comprises a vent 48 defining anaperture 50 through tank 12, a vent member 52 for selectively openingand blocking aperture 50, a vent closure spring 54 for urging ventmember 52 to a closed sealed position (FIGS. 1, 4, 5, and 7 ), a scoop56 extending at least partially over aperture 50, and a slender member58 coupling vent member 52 to gate valve assembly 18. The term, “ventmember” refers to any structure for selectively blocking and unblockingan aperture. A few examples of vent member 52 include a plate, a disc, aplug, a diaphragm, a ball, a flap, a cone, a partially spherical body,etc. Some example modes of vent member movement include translating,pivoting, expanding, contracting, bending, and various combinationsthereof.

Some examples of vent 48 comprise an inlet well 60 extending down intothe tank's chamber 22 toward the vent's aperture 50. Inlet well 60 has abrim 62 at an upper surface 64 of tank 12. Brim 62 is the outerperiphery of inlet-well 60. In some examples of vent 48, a lower end 60′of inlet-well 60 defines aperture 50 between the tank's chamber 22 andan outside atmosphere 66 surrounding aircraft 14. In some examples,inlet-well 60 includes an upstream surface 68 and a downstream surface70. Aperture 50 and downstream surface 70 are behind upstream surface 68with respect to the forward direction 40 along roll axis 34. In someexamples, upstream surface 68 extends downward from brim 62 towardaperture 50, and downstream surface 70 extends upward from aperture 50.In some examples, inlet well 60 is 3D printed and is comprised of carbonfiber reinforced polypropylene.

In some examples, upstream surface 68 is sloped more gradually thandownstream surface 70, as viewed along an imaginary plane 72, whereinimaginary plane 72 is defined as intersecting a centerpoint 74 ofaperture 50 and lying perpendicular to pitch axis 36. In some examples,the aperture's centerpoint 74 is laterally centered relative to aircraft14 and roll axis 34. In other examples, the aperture's centerpoint 74 islaterally offset to the left or right of roll axis 34. Some examples ofvent system 10 include two vents 48 or 48′ on either side of roll axis34. Some examples of vent system 10 include more than two vents 48 or48′.

In some examples, the gradual slope of upstream surface 68 promotes abeneficial Coanda effect, whereby upstream surface 68 tends to draw airto itself and thereby effectively direct that air down toward aperture50. In some examples, upstream surface 68 curves smoothly alongimaginary plane 72 to gradually direct the airflow downward. In someexamples, upstream surface 68 is substantially linear along imaginaryplane 72 to simplify manufacturing of vent 48. In some examples,upstream surface 68 lies at an obtuse acute angle 76 of less than 45degrees to roll axis 34 to promote the Coanda effect.

Inlet-well 48 placing aperture 50 at a recessed elevation below thetank's upper surface 64 in combination with the Coanda effect enablesvent 48 to draw an ample amount of air down through aperture 50 and intotank 12 without creating a prominent upward protrusion that couldotherwise significantly obstruct a pilot's view. In some examples,however, a relatively low-profile scoop 56 can be added to increase theairflow through aperture 50 and to help shield windshield 32 frombacksplash when vent 48 is open.

To minimize obstructing the pilot's view, some examples of scoop 56extend only a certain height 78 above brim 62, wherein certain height 78is less than a well-depth 80 of inlet-well 60. In some examples,well-depth 80 is preferably at least one inch lower than brim 62 torealize the benefit of a recessed vent. In some examples, the certainheight 78 is less than three inches to avoid creating a significantobstruction to the pilot's view. In some examples, the scoop's certainheight 78 is less than two inches, and well-depth 80 is greater than twoinches to provide a good compromise between vent inlet airflow andminimal obstruction to the pilot's view. In some examples, the scoop'sheight 78 is about 1.5 inches, and well-depth 80 is about three inchesfor best results. To realize at least a minimal benefit of aperture 50being recessed, inlet-well 60 at aperture 50 is at least one inch lowerthan brim 62. In some examples, as shown in FIG. 10 , a scoop 56′ has acertain height 78 that is substantially equal to zero (i.e., scoop 56′is substantially flush with brim 62).

To further increase vent airflow while reducing backsplash, someexamples of scoops 56 and 56′ extend in forward direction 40 out overaperture 50. With the addition of scoop 56 or 56′, some backsplash offluid 16 might collect in a lower rear area 82 of vent-well 60. In someexamples, a drain tube 84 can be used for draining this collection offluid 16.

In some examples, drain tube 84 has an inlet 86 and an outlet 88. Inlet86, in some examples, is in fluid communication with inlet-well 60 at apoint in lower rear area 82 above aperture 50 and below brim 62. In someexamples, the drain tube's outlet 88 is below the tube's inlet 86 andbelow aperture 50. In some examples, drainage of fluid 16 through draintube 84 is directed back into tank 12, directed down into a separatewaste collection tank, or simply released into the surroundingatmosphere 66. The term, “tube” refers to any fluid passageway. Someexamples of a tube include a pipe, a hose, a conduit, a drilled hole, achannel, a gutter, and various combinations thereof.

In some examples, to reduce assembly costs and avoid leakage points,inlet-well 60 is integrally formed seamlessly in the tank's uppersurface 64. In such examples, inlet-well 60 and the tank's upper surface64 are both made of the same material. In some examples, the tank'supper surface 64 is part of a lid that is hinged to the rest of tank 12,whereby the hinged lid provides access to chamber 22.

In some examples, tank 12 adjoins a cowl 90 of aircraft 14. In someexamples, cowl 90 is comprised of a first material (e.g., aluminumalloy), tank 12 and inlet-well 60 are each comprised of a secondmaterial (e.g., a polymer, fiberglass, or some other composite), and thefirst material is different than the second material. The two materialsbeing different from each other allow the use of optimal materials eachbeing uniquely suitable for an aircraft cowl and a tank's wall.

In some examples, vent closure spring 54 urges vent member 52 to itsclosed position. Vent closure spring 54 is schematically illustrated torepresent any resilient member capable of urging vent member 52 to itsclosed position. Some examples of vent closure spring 54 include atorsion spring, a compression spring, an extensions spring, a leafspring, a constant force spring, an elastic cord, an elastic strap, apneumatic spring, a bellows, etc. In some examples, a certain level ofvacuum (e.g., −0.5 psig) in chamber 22 overcomes vent closure spring 54and thereby forces vent member 52 to its open position. A vacuum of −0.5psig, however, can delay the release of fluid 16 out from within tank12.

To overcome this problem, some examples of vent system 10 includeslender member 58. The term, “slender member” refers to any elongatestructure having a length that is at least ten times greater than itswidth. Some examples of slender member 58 are rigid. Other examples ofslender member 58 are more flexible or pliable. Some examples of slendermember 58 include a cable, a chain, a nylon strap, an elastic strap, anextension spring, a wire, a rope, a cord, a rod, a bar, a linkage, alinkage assembly, a tube, and various combinations thereof.

In some examples, slender member 58 couples vent member 52 to gate valveassembly 18 such that gate 20 moving between the closed position and theopen position causes vent member 52 to move respectively between itssealed position and the unsealed position. In some examples, ventclosure spring 54 holds vent member 52 at the sealed position when gate20 is in its closed position. In some examples, slender member 58overpowers vent closure spring 54 to force vent member 52 to itsunsealed position when gate 20 is in the open position.

In some examples, when gate 20 is in the closed position, slender member58 is slack (FIGS. 5 and 7 ), which allows vent closure spring 54 toclose vent member 52 without appreciable resistance from slender member58. In some examples, when gate 20 is in the open position, slendermember 58 is taut (FIGS. 6, 8, and 9 ) and forces vent member 52 to itsunsealed position.

It should be appreciated by those of ordinary skill in the art thatpoints 92 and 94 to which slender member 58 respectively connects tovent member 52 and gate valve assembly 18 can be at any suitablelocations. In some examples, point 92 is on a lug 96 extending from ventmember 52. In some examples, point 94 is on a lug 98 extending from gate20, as shown in FIGS. 5, 6, 7, and 8 . In some examples, as shown inFIG. 9 , point 94 can be attached to a link 100 connecting gate 20 to agate actuator 102.

Gate actuator 102 is schematically illustrated to represent any meansfor powering the movement of gate 20. Some examples of gate actuator 102include a motor, a hydraulic cylinder, a gearbox, a linkage assembly,and various combinations thereof. In some examples, a linkage assembly,gears, or some other mechanism couples multiple gates 20 to gateactuator 102, so the multiple gates 20 open and close in unison.

In some examples, vent system 10 includes two or more vents 48, as shownin FIG. 9 . In some examples, vent system 10 includes a front vent 48 aand a rear vent 48 b. In some examples, each vent 48 a and 48 b aresubstantially identical to vent 48. Vents 48 a and 48 b have a strategictandem arrangement such that an upper surface 104 of the front vent'sscoop 56 utilizes the Coanda effect to direct air 106 into an inlet 50of the rear vent 48 b. In some examples, rear vent 48 b can capturebacksplash that might escape front vent 48 a, thus minimizing the amountof backsplash that might otherwise reach windshield 32.

In the example shown in FIGS. 11 and 12 an example vent member 52′ inthe form of a vertically translating plate and an example vent closurespring 54′ is in the form of a compression spring. Vent closure spring54′ urges vent member 52′ to its sealed position (FIG. 11 ). When gate20 opens, slender member 58 pulls vent member 52′ to its unsealedposition (FIG. 12 ). In some examples one or more spokes 110 helpposition vent member 52′ in a radial direction. In some examples, toachieve sufficient ventilating airflow, the vertical travel distance ofvent member 52′ is at least twenty percent of the vent member's outerdiameter. In some examples, the vertical travel distance of vent member52′ is about 2.5 inches.

In addition or alternatively, some examples of vent system 10 have twomodes of operation, e.g., a first mode and a second mode. Examples offirst mode are shown in FIGS. 13 and 14 . Examples of second mode areshown in FIGS. 2, 6, 8, 9 and 10 .

In some examples of the first mode, vent member 52 or 52′ of vent 48 or48′ moves independent of gate 20 from the sealed position to theunsealed position in response to the chamber pressure (i.e., the airpressure in chamber 22) decreasing a predetermined amount below theatmospheric pressure. In some examples, the predetermined amount is 0.8psig below atmospheric pressure (i.e., −0.8 psig). So, in some examples,if the air pressure differential across vent member 52 or 52′ reaches orexceeds 0.8 psig (at least 0.8 psig of vacuum in chamber 22), then thepressure differential will open the vent. In some examples, thepredetermined amount is between about 1.5 psig to 2 psig belowatmospheric pressure.

Such a first mode of operation helps avoid collapsing or otherwisedamaging tank 12 under certain adverse pressure conditions. Forinstance, in some cases, fill valve 112 or gate 20 might leak. The lostfluid 16 could create excessive vacuum in chamber 22. In other cases,changes in elevation of aircraft 14 might create an adverse vacuum inchamber 22.

As a means for preventing damagingly high vacuum from developing withinchamber 22, the first mode of operation allows vent member 52 and 52′ toopen independent of gate 20. So, in the first mode, vent members 52 and52′ can move regardless of whether gate 20 is open or closed.

In the second mode, vent members 52 and 52′ can move independent of thechamber pressure from the sealed position to the unsealed position inresponse to gate valve assembly 10 applying a predetermined amount oftension 114 to slender member 58. The predetermined amount of tension114 is that which is needed to overcome the force of vent closure spring54 or 54′.

The second mode allows vent members 52 and 52′ to open even when thereis no pressure differential between the air pressure in chamber 22 andthe outside atmosphere. The second mode of operation allows aircraft 14to release fluid 16 at a maximum fluid flow rate, as vent system 10 doesnot require a vacuum or −0.5 psig in chamber 22 in order to functionproperly.

To prevent accidentally damaging vent system 10, some examples ofslender member 58 include a tension-limiting spring 116 (e.g., anextension spring). Tension-limiting spring 116 can be installed anywherealong the length of slender member 58. If for some reason slender member58 tries to exert excessive pulling force on vent member 52 or 52′,tension-limiting spring 116 will yield (resiliently extend) to limit theslender member's pulling force (tension 114). Tension-limiting spring116, for example, prevents an installer or mechanic from adjustingslender member 58 so tightly that it damages vent system 10. Undernormal operation, tension-limiting spring 116 remains unextendedregardless of whether vent system 10 is open or closed.

Although certain example methods, apparatus and articles of manufacturehave been disclosed herein, the scope of coverage of this patent is notlimited thereto. On the contrary, this patent covers all methods,apparatus and articles of manufacture fairly falling within the scope ofthe claims of this patent.

1. A vent system for an aircraft that can disperse a fluid whilein-flight, the aircraft includes a nose, a tail, and a cockpit with awindshield; the aircraft defining a roll axis, a pitch axis, and a yawaxis; the aircraft extending lengthwise along the roll axis in a forwarddirection from the tail to the nose, the aircraft extending widthwisealong the pitch axis, the aircraft extending along the yaw axis in anupward direction from a lower portion of the aircraft to an upperportion of the aircraft, the cockpit being between the tail and the nosewith respect to the roll axis; the roll axis, the yaw axis, and thepitch axis lying perpendicular to each other, the vent systemcomprising: a tank between the cockpit and the nose, the tank defining achamber for containing the fluid; a gate valve assembly underneath thetank and in fluid communication with the chamber, the gate valveassembly includes a gate that is movable selectively to an open positionto release the fluid from the tank and a closed position to retain thefluid within the tank; a vent comprising a brim at an upper surface ofthe tank, the vent includes an inlet-well extending down from the brim,the inlet-well defining an aperture between the chamber and an outsideatmosphere surrounding the aircraft, the aperture being at a lower endof the inlet-well, the inlet-well includes an upstream surface and adownstream surface, the aperture and the downstream surface are behindthe upstream surface with respect to the forward direction along rollaxis, the upstream surface extends downward from the brim toward theaperture, the downstream surface extends upward from the aperture; avent member of the vent is movable selectively to a sealed position andan unsealed position relative to the aperture, the vent member blockingfluid communication through the aperture when the vent member is in thesealed position, the aperture placing the chamber in open fluidcommunication with the outside atmosphere when the vent member is in theunsealed position; and with respect to an imaginary plane passingthrough a centerpoint of the aperture and lying perpendicular to thepitch axis, the inlet-well at the aperture is at a well-depth of atleast one inch lower than the brim at the upper surface of the tank andat least a portion of the upstream surface is sloped at an obtuse anglerelative to the roll axis.
 2. The vent system of claim 1, wherein theobtuse angle is less than 45 degrees.
 3. The vent system of claim 1,wherein the upstream surface curves along the imaginary plane.
 4. Thevent system of claim 1, wherein the upstream surface is sloped moregradually than the downstream surface along the imaginary plane.
 5. Thevent system of claim 1, further comprising a scoop that extends to acertain height above the brim and extends at least partially over theaperture.
 6. The vent system of claim 5, wherein the well-depth isgreater than the certain height of the scoop.
 7. The vent system ofclaim 1, further comprising a scoop that extends at least partially overthe aperture, and the scoop is substantially flush with the uppersurface of the tank.
 8. The vent system of claim 1, wherein the tankadjoins a cowl of the aircraft, the cowl is comprised of a firstmaterial, the tank and the inlet-well are each comprised of a secondmaterial, and the first material is different than the second material.9. The vent system of claim 1, further comprising a drain tube definingan inlet and an outlet, the inlet being in fluid communication with theinlet-well at a point above the aperture and below the brim, and theoutlet being below the inlet and below the aperture.
 10. The vent systemof claim 1, further comprising: a slender member having a length and awidth, the length being at least ten times greater than the width, theslender member coupling the vent member to the gate valve assembly suchthat the gate moving between the closed position and the open positioncauses the vent member to move respectively between the sealed positionand the unsealed position; a vent closure spring coupled to the ventmember, the vent closure spring urging the vent member to the sealedposition; and the vent closure spring holding the vent member at thesealed position when the gate is in the closed position, the slendermember overpowering the vent closure spring to hold the vent member atthe unsealed position when the gate is in the open position.
 11. Thevent system of claim 10, wherein the slender member includes atension-limiting spring.
 12. A vent system for an aircraft that candisperse a fluid while in-flight, the aircraft includes a nose, a tail,and a cockpit with a windshield; the aircraft defining a roll axis, apitch axis, and a yaw axis; the aircraft extending lengthwise along theroll axis in a forward direction from the tail to the nose, the aircraftextending widthwise along the pitch axis, the aircraft extending alongthe yaw axis in an upward direction from a lower portion of the aircraftto an upper portion of the aircraft, the cockpit being between the tailand the nose with respect to the roll axis; the roll axis, the yaw axis,and the pitch axis lying perpendicular to each other, the vent systemcomprising: a tank between the cockpit and the nose, the tank defining achamber for containing the fluid; a gate valve assembly underneath thetank and in fluid communication with the chamber, the gate valveassembly includes a gate that is movable selectively to an open positionto release the fluid from the tank and a closed position to retain thefluid within the tank; a vent at an upper portion of the tank and beingabove the gate valve assembly, the vent defining an aperture between thechamber and an outside atmosphere surrounding the aircraft, the ventincluding a vent member that is movable selectively to a sealed positionand an unsealed position, the vent member blocking fluid communicationthrough the aperture when the vent member is in the sealed position, theaperture placing the chamber in open fluid communication with theoutside atmosphere when the vent member is in the unsealed position; avent closure spring coupled to the vent member, the vent closure springurging the vent member to the sealed position; and a slender memberhaving a length and a width, the length being at least ten times greaterthan the width, the slender member coupling the vent member to the gatevalve assembly such that the gate moving between the closed position andthe open position causes the vent member to move respectively betweenthe sealed position and the unsealed position, the vent closure springholding the vent member at the sealed position when the gate is in theclosed position, the slender member overpowering the vent closure springto hold the vent member at the unsealed position when the gate is in theopen position.
 13. The vent system of claim 12, wherein the slendermember is a pliable elongate member.
 14. The vent system of claim 12,wherein the slender member includes a tension-limiting spring.
 15. Thevent system of claim 12, wherein the vent includes a brim at an uppersurface of the tank, the vent includes an inlet-well extending down fromthe brim, the inlet-well of the vent defines the aperture, the apertureis at a lower end of the inlet-well, the inlet-well includes an upstreamsurface and a downstream surface, the aperture and the downstreamsurface are behind the upstream surface with respect to the forwarddirection along roll axis, the upstream surface extends downward fromthe brim toward the aperture, the downstream surface extends upward fromthe aperture; and with respect to an imaginary plane passing through acenterpoint of the aperture and lying perpendicular to the pitch axis,the inlet-well at the aperture is at a well-depth of at least one inchlower than the brim at the upper surface of the tank and at least aportion of the upstream surface is sloped at an obtuse angle relative tothe roll axis.
 16. The vent system of claim 15, wherein the obtuse angleis less than 45 degrees.
 17. The vent system of claim 15, wherein theupstream surface is sloped more gradually than the downstream surfacealong the imaginary plane.
 18. The vent system of claim 15, furthercomprising a scoop that extends to a certain height above the brim andextends at least partially over the aperture.
 19. The vent system ofclaim 18, wherein the well-depth is greater than the certain height ofthe scoop.
 20. The vent system of claim 18, wherein the certain heightof the scoop is less than three inches.
 21. The vent system of claim 15,further comprising a scoop that extends at least partially over theaperture, and the scoop is substantially flush with the upper surface ofthe tank.
 22. A vent system for an aircraft that can disperse a fluidwhile in-flight, the aircraft includes a nose, a tail, and a cockpitwith a windshield; the aircraft defining a roll axis, a pitch axis, anda yaw axis; the aircraft extending lengthwise along the roll axis in aforward direction from the tail to the nose, the aircraft extendingwidthwise along the pitch axis, the aircraft extending along the yawaxis in an upward direction from a lower portion of the aircraft to anupper portion of the aircraft, the cockpit being between the tail andthe nose with respect to the roll axis; the roll axis, the yaw axis, andthe pitch axis lying perpendicular to each other, the vent systemcomprising: a tank between the cockpit and the nose, the tank defining achamber for containing the fluid, the chamber experiencing a chamberpressure; a gate valve assembly underneath the tank and in fluidcommunication with the chamber, the gate valve assembly includes a gatethat is movable selectively to an open position to release the fluidfrom the tank and a closed position to retain the fluid within the tank;a vent at an upper portion of the tank and being above the gate valveassembly, the vent defining an aperture between the chamber and anoutside atmosphere surrounding the aircraft, the atmosphere being at anatmospheric pressure, the vent including a vent member that is movableselectively to a sealed position and an unsealed position, the ventmember blocking fluid communication through the aperture when the ventmember is in the sealed position, the aperture placing the chamber inopen fluid communication with the outside atmosphere when the ventmember is in the unsealed position; a vent closure spring coupled to thevent member, the vent closure spring urging the vent member to thesealed position; and a slender member having a length and a width, thelength being at least ten times greater than the width, the slendermember coupling the vent member to the gate valve assembly so as toprovide the vent system with two modes of operation including: a) afirst mode, wherein the vent member moves independent of the gate fromthe sealed position to the unsealed position in response to the chamberpressure decreasing a predetermined amount below the atmosphericpressure; and b) a second mode, wherein the vent member movesindependent of the chamber pressure from the sealed position to theunsealed position in response to the gate valve assembly applying apredetermined amount of tension to the slender member.
 23. The ventsystem of claim 22, wherein the slender member includes atension-limiting spring.